• ↑ Serum Ca²⁺ via:
o Bone resorption
o Renal calcium reabsorption
o Activates vitamin D → ↑ gut calcium absorption
• Also causes phosphate excretion
• Autonomous PTH secretion (usually parathyroid adenoma)
• Features: "stones, bones, groans, and psychiatric overtones"
o Renal stones, bone pain, abdominal symptoms, depression, confusion
• Labs: ↑ Ca²⁺, ↑ PTH, ↓ phosphate, ↑ ALP
• Imaging: Sestamibi scan or neck ultrasound
• Treatment: parathyroidectomy if symptomatic or meeting criteria (age <50, renal/bone involvement)
• Low calcium → compensatory ↑ PTH
• Causes:
o Chronic kidney disease (↓ vitamin D activation, phosphate retention)
o Vitamin D deficiency
• Labs: ↓ Ca²⁺, ↑ PTH, ↑/normal phosphate, ↑ ALP
• Treatment: correct underlying cause (e.g. vit D supplementation, phosphate binders in CKD)
• Features: tetany, perioral tingling, seizures, Chvostek’s & Trousseau’s signs, prolonged QT
• Causes:
o Post-surgical hypoparathyroidism
o Hypomagnesaemia (impairs PTH secretion)
o Vitamin D deficiency
o CKD
• Labs: ↓ Ca²⁺, consider Mg²⁺, PTH, vitamin D levels
• Treatment: IV calcium gluconate (acute), oral calcium/vit D (chronic)
• Vitamin D deficiency → defective bone mineralisation
• Causes: malabsorption, CKD, anticonvulsants, poor sunlight/diet
• Features: bone pain, muscle weakness, fractures, waddling gait
• Labs: ↓ Ca²⁺, ↓ phosphate, ↑ ALP, ↓ 25(OH) vitamin D
• Treatment: vitamin D and calcium replacement
• Reduced bone mass with normal mineralisation
• Risk factors: age, menopause, steroids, smoking, alcohol, immobility
• Common sites: spine, hip, wrist
• Diagnosis: DEXA scan – T-score < –2.5
• Labs: normal Ca²⁺, phosphate, ALP
• Treatment:
o Bisphosphonates (alendronate – osteonecrosis of jaw risk)
o Calcium + vitamin D
o Lifestyle: weight-bearing exercise, smoking cessation
o Consider: denosumab, HRT, teriparatide (in severe cases)
• Focal disordered bone remodelling: ↑ osteoclast and osteoblast activity
• Features: bone pain, deformity, hearing loss (skull involvement), high-output cardiac failure (rare)
• Labs: ↑ ALP, normal Ca²⁺ and phosphate
• Imaging: X-ray – cortical thickening, lytic/sclerotic areas
• Treatment: bisphosphonates (e.g. zoledronate), analgesia
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
